Portion of a bottom surface of a shoe sole



FIG. 1 is a front perspective view of a portion of a bottom surface of a shoe sole showing my new design;

FIG. 2 is a bottom plan view thereof;

FIG. 3 is a cross-section taken along the line 3--3 of FIG. 2;

FIG. 4 is a cross-section taken along the line 4--4 of FIG. 2; and,

FIG. 5 is a rear perspective view thereof.

The broken line showing of a shoe upper and the remaining portion of the sole is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a portion of a bottom surface of a shoe sole, as shown and described. 